The present invention relates to a hingeless ventilator for ventilating a compartment or enclosure through a defining wall thereof. Hingeless ventilators are well known in the art and there are a number of Kelly and Kelly et al. patents on hingeless ventilators particularly designed for ventilating a cab or other compartment of a vehicle. Among these patents are U.S. Pat. Nos. 3,102,464; 3,358,576; 3,839,950; 4,452,129; 5,020,425; and 5,766,068. All of these patents describe two-way hingeless ventilators having closure members openable in one direction to draw air into the compartment, and openable in an opposite direction to exhaust air from the vehicle compartment. Thus, these types of ventilators that can be opened in both directions are conventionally referred to as "two-way" hingeless ventilators.
U.S. Pat. No. 3,375,772 to Kelly et al. describes a "one-way" hingeless ventilator having a cover member that is swingable in an arc in one direction between open and closed positions. The device described in the '772 patent includes a tension rod mounted on a frame for holding the cover member in position. The cover has a guide secured to an inner face thereof having a guide way which is slidably engaged with the tension rod. This device, however, cannot be used as a two-way hingeless ventilator and, thus, lacks the inherent utility of a two-way hingeless ventilator.